Quantum Parameter Estimation Under The Quantum Open System

Quantum parameter estimation uses the quantum system as a probe to measure and estimate the physics parameter,it is important in both experiment and theory.In reality,quantum system is inevitably influenced by the environment and interacts with it.Therefore,it induces the dissipation of energy and decoherence.As a result,we need make use of the quantum open system theory to describe the behavior of the quantum system.Based on these,we study the quantum parameter estimation under the quantum open system and mainly focus on the influence of non-Gaussian noise on the accuracy of the parameter estimation.Meanwhile,it is reflected by the behavior of the quantum Fisher information.Specially,we adopt a spin-1/2 system to estimate the intensity of the magnetic field,meanwhile the system is influenced by the random telegraph noise and colored noise respectively.At first,we choose our initial state and it can make sure the quantum Fisher information of the output state reaches its maximum value.Then the qubit is subjected to the magnetic field and at the same time it interacts with the noise.After some time,we measure the system to get the information about our parameter.In the process,we give the total Hamiltonian of the system and calculate the density matrix of the state,finally we get the analytic expression of the quantum Fisher information under the two noise.Afterwards,we get the behavior of the quantum Fisher information and analyze it at length.We find that the quantum Fisher information is greatly affected by the noise parameter.To be specific,in the random telegraph noise condition,both strong coupling and weak coupling cases are good for the parameter estimation.While in the colored noise case,the accuracy of the parameter estimation decreases with? firstly and then increases with it.